Famed promoter Don King, who worked on some of Ali's most famous fights, also chimed in. “It’s a sad day for life, man," he said. I loved Muhammad Ali, he was my friend. Ali will never die. Like Martin Luther King his spirit will live on, he stood for the world.”

Those are merely a few of a score of acknowledgements pouring in for the fighter. Ali's death is being felt by people from the world of boxing and beyond, as expressed on social media.